WO1995020023A1

WO1995020023A1 - Liquid treatment apparatus

Info

Publication number: WO1995020023A1
Application number: PCT/NZ1995/000006
Authority: WO
Inventors: Ronald James Gilbert
Original assignee: Ronald James Gilbert
Priority date: 1994-01-23
Filing date: 1995-01-20
Publication date: 1995-07-27
Also published as: CA2181888A1; AU1547195A; AU740805B2

Abstract

A process and apparatus for treating contaminated liquids for reuse incorporating filtering and degasifying. The process enables the decontamination and degasifying to be carried out away from or at the site of the contaminated liquid and includes means by which filtering materials can be automatically replaced.

Description

Liquid Treatment Apparatus

TECHNICAL FIELD

This invention relates to a liquid treatment apparatus and methods of treating liquids using such an apparatus For convenience only, the present invention will be described with reference to liquid treatment apparatus and methods for the treatment of liquids such as transformer oils for which the invention may be particularly applicable. However, it is to be understood that it is not to be limited as such. Moreover, because the invention may have other applications it is to be understood that the prior art and possible embodiments of the invention as discussed below are given by way of example only.

BACKGROUND ART

Conventional apparatus and methods for the treatment of transformer oils which have become contaminated with contaminants such as water, acidic compounds, other products of oxidation and colloidal contaminants generally involve heating and filtering the oil, treatment with an adsorbent such as Fuller's earth to adsorb contaminants from the oil, and subsequently degasifying the oil. Additional processes such as passing the liquid through a coalescer to coalesce water in the liquid and hence separate it out, and/or centrifuging the liquid to remove free water may also be incorporated into the operation.

Heating is generally carried out by electrical heating with an element immersed in the oil. However, due to the relatively high temperature of the element required to obtain adequate heat transfer to the oil, overheating of the oil can occur at the surface of the element with the formation of additional impurities.

Centrifuging to remove the water can have adverse effects on the liquid due to the centrifugal loadings and shear stresses to which the liquid is subjected which can affect the chemical chains of molecules and alter the liquid properties.

Furthermore, with conventional apparatus and methods, the adsorbent which is contained in an adsorbent container has a limited life and must be periodically replaced. However, due to the tendency for conventional adsorbents such as Fuller's earth to coalesce together in the container, replacement of the spent adsorbent generally requires manual removal. Hence full automation of the liquid treatment method and apparatus is not possible, and labour and operating costs can be high. Moreover, the adsorbent replacement generally results in loss of any liquid remaining in the adsorbent.

Conventional methods of degasifying the oil subsequent to filtering and adsorption treatment generally involve holding the oil in a container as a single body of liquid and subjecting this to a vacuum so that contaminants boil off and come out of solution. Since it takes time for complete degasification by this method, the oil is generally recirculated through the system several times until the required degree of purity is obtained. This requirement for recirculation involves additional time and hence adds to the costs and inconvenience of treating the oil.

The above disadvantages of the conventional methods and apparatus for the treatment of oils thus result in a relatively expensive operation which cannot be easily automated. It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF THE INVENTION

According to the present invention there is provided a process for treating contaminated liquids, said process comprising the steps of;

(a) passing said contaminated liquid through a filter to remove particles from said liquid,

(b) heating the filtered liquid in a heater;

(c) passing said heated liquid through an adsorber containing a granular adsorbent capable of removing contaminants from said liquid; and (d) degasifying the liquid.

The process may include the steps of;

(a) isolating a container containing granular material from an inlet and outlet,

(b) applying a pressure differential across granular material contained in said container,

(c) allowing liquid contained in said container to flow out of said container through a liquid outlet as a result of said pressure differential, while preventing granular material in said container from flowing out of said container, (d) closing off said liquid outlet , (e) discharging said granular material from said container by opening a granular material discharge outlet to allow granular material contained therein to flow out of said container under a pressure differential, (f) closing said granular material outlet and reducing the pressure in said container, and (g) opening a granular material inlet to said container to allow a predetermined amount of granular material to flow into said container.

The process may further include said step of applying a pressure differential across said granular material involves pressurising an inlet to said container and connecting said liquid outlet from said container to a collection chamber (buffer collection tank), and the step of discharging granular material from said container involves allowing a pressure inside said container to increase to a predetermined pressure above atmospheric pressure, and then opening said discharge outlet to discharge granular material under the resultant pressure differential into a container at atmospheric pressure, and recycling liquid collected in said collection chamber back into said liquid treatment apparatus.

The process may include degasifying comprises the steps of;

(a) heating a liquid to be treated to a predetermined temperature, and then passing said liquid into a container maintained at a reduced pressure,

(b) causing said liquid to flow over a surface or surfaces inside said container as a thin film, so that liquid contaminants contained in said liquid evaporate from said liquid, and gaseous contaminants dissolved in said liquid come out of solution and separate from said liquid, and until a predetermined purity of liquid is obtained, and (c) pumping said purified liquid from said container.

According to a further aspect of the present invention there is provided a liquid treatment apparatus for removal of contaminants from a liquid, said apparatus comprising:- inlet means for inputting a liquid to be treated by said apparatus into said apparatus, outlet means for discharging said liquid from said apparatus after treatment by said apparatus, heating means for heating said liquid, filter means for filtering contaminants from said liquid, adsorption means for adsorbing contaminants from said liquid, evaporator/degasifier means for evaporating and separating out liquid and gaseous contaminants contained in said liquid, pumping means for pumping said liquid from said inlet means through said filter means, adsorption means, heating means, and evaporator/degasifier means to said outlet means, and control means for controlling the operation of various components of the apparatus to enable semi automatic or fully automatic operation.

The apparatus may further comprise coalescer means for coalescing liquid impurities in said liquid for subsequent removal from said liquid.

The apparatus may further comprise material handling means for facilitating replacement of adsorbent/filter material in said filter means and said adsorber means. Said heating means may comprise a heat source for heating a primary heating fluid, and a heat exchanger for exchanging heat from said primary fluid to said liquid being treated.

The evaporator/degasifier means may comprise; a vacuum chamber having an inlet and an outlet, means for producing a vacuum in said vacuum chamber, and means for producing a thin film flow of said liquid inside said vacuum chamber.

The heating means for the liquid treatment apparatus according to the present invention may comprise an oil burner type heater for heating a primary heating medium, and one or more heat exchangers for transferring heat from the primary medium to the liquid being treated.

With such an arrangement the temperature of the secondary heat transfer surfaces may be easily controlled to ensure it does not exceed an amount which would be detrimental to the liquid being treated. For example with the treatment of transformer oils this temperature would be kept below 60°C.

Heat exchangers may be provided at different stages of the treatment process to obtain optimum temperature conditions. For example, a first higher temperature heat exchanger may be provided for heating liquid in the evaporator/degasifier, a second medium temperature heat exchanger may be provided for heating liquid at the inlet, and a third lower temperature heat exchanger may be provided intermediate in the process to maintain a suitable temperature of the liquid. The filter/adsorber means may comprise a container filled with a granular adsorber/filter material, the container having a liquid inlet and outlet, and a granular material inlet and outlet The liquid outlet may have a screen for containing granular material in the container while allowing liquid to pass from the container to the liquid outlet. A suitable material for the adsorber/filter may be a granular material such as Attapulgite™ mined by Malina Holdings in Australia. This material has been found to maintain its granular characteristics even when spent as an adsorbent, and so can be easily flushed from the container, thus making it suitable for an automated material handling system.

In addition, standard types of commercial filters may be used for filtering contaminants from the liquid. For example a proprietary type of industrial filter such as a Zeta Plus® filter having a filter media with a high contaminant holding capacity may be suitable. Several such filters may be used arranged in series with provision for isolation of any one filter to enable the filter element to be changed when required. A filter condition indicator may be incorporated into a control system of the apparatus to indicate when the element requires changing.

With the evaporator/degasifier according to the present invention, the vacuum producing means may comprise a pump such as a lobe type or star type hydraulic pump. This may be housed inside a sealed container with an outlet from the container connected to an outlet from the pump, and an inlet to the container connected to the vacuum chamber of the evaporator/degasifier. Housing the pump inside the sealed container helps to overcome problems with vacuum sealing. Hydraulic lines for powering the pump may be passed though sealed openings in the wall of the container. With such an arrangement a vacuum of at least 5 Torrs may be applied to the vacuum chamber of the evaporator/degasifier.

The means for thin film flow production in the evaporator/degasifier may comprise a plurality of elongate tubes arranged in vertical orientation adjacent to each other, the tubes being supported at an upper end thereof by a baffle plate which is fixedly attached to the vacuum chamber and which seals a passage between the tubes so that liquid can only flow though the tubes in a downward direction. An additional baffle plate may also be provided at the lower end of the tubes so as to seal the outer surface of the tubes. A heating liquid may then be circulated around the tubes to heat or maintain the temperature of the liquid as it flows down the tubes Preferably the tube diameter and length dimensions would be chosen to provide a thin film of a suitable surface area and thickness to enable impurities to be removed under the vacuum while the liquid flowed through the evaporator/degasifier. Having a flow length (tube length) of 1200 mm under a vacuum of 9.5 Torr with a liquid temperature of approximately 55°C may be sufficient to reduce the residual gas/liquid impurities in the liquid to a sufficient amount, so that the liquid treatment apparatus can treat the liquid in a single pass.

Preferably the openings to the vertically orientated tubes are disposed above the surface of the baffle plate.

The coalescer may comprise a standard coalescer for removal of liquids from a liquid.

The material handling means may comprise;

(a) a pressurisation system for applying a pressure across the adsorber/filter container between the inlet and outlet, (b) evacuation means such as a vacuum fan for reducing a pressure inside the container,

(c) a first valve for selectively opening/closing the container liquid inlet to a liquid supply,

(d) a second valve for selectively opening/closing the container granular material inlet to a granular material supply,

(e) a third valve for selectively opening/closing a container pressurisation inlet to the pressurisation system,

(f) a fourth valve for selectively opening/closing a container evacuation inlet to the evacuation means,

(g) a fifth valve for selectively opening/closing the container liquid outlet to a liquid outlet,

(h) a sixth valve for selectively opening/closing the container liquid outlet to a liquid buffer container,

(i) a seventh valve for selectively opening/closing the container granular material outlet to a spent material dump container, and

(j) a control system for controlling an opening/closing sequence of the valves such that liquid contained in the granular material is first forced out of the container under pressure from the pressurisation means into the liquid buffer container, granular material is then forced out of the container into the spent material dump container, and then granular material is drawn into the container from a granular material supply via the granular material inlet. The material handling means may also incorporate valving and controls to facilitate the replacement of filter or coalescer elements. Such equipment may involve valving to isolate the container having the element to be changed, and piping to drain off a predetermined amount of liquid from the container into the above-mentioned liquid buffer container to allow space for a new dry filter or coalescer element to be inserted without spilling. With both the filter/adsorbent change and the filter/coalescer change, liquid contained in the buffer container may be recycled back into the system for treatment thereby avoiding waste, and enabling continuous operation of the apparatus.

The pressurisation system for the material handling means may comprise one or more compressors which may be electrically or hydraulically driven, arranged to apply a positive pressure to the inlet of the adsorber/filter container. A negative pressure may be produced on the outlet of the container by drawing a vacuum on the liquid buffer container. With this arrangement the pressure inside the filter/adsorber container may be kept to a minimum thereby enabling simpler design and manufacture.

The evacuation system for the material handling means may comprise a suction fan drawing from the adsorber/filter container and discharging into a dust collector. The granular material inlet to the container may be arranged so that a cyclone type flow pattern is produced, with the granular material dropping down into the container and the air being drawn out from a central outlet in the top of the container. The granular material supply for the materials handling means may include a storage hopper for storing a predetermined amount of granular material ready for charging into an adsorber/filter container. This hopper may be maintained in a full condition by a separate valving means which opens the hopper to the evacuation means whereby a vacuum is produced in the hopper to enable granular material to be drawn into the hopper through an inlet pipe from a granular material supply tank.

The liquid buffer container for the material handling means may be a cylindrical container of sufficient capacity to hold at least the amount of liquid discharged from a filter/adsorber during adsorbent replacement, and preferably also the amount of liquid discharged at the time of a filter/coalescer change. The buffer container may be provided with a control system and valving to enable the liquid inside to be recycled back into the liquid treatment apparatus.

The valves in the materials handling means may preferably be two way or three way valves so that closing of one valve automatically opens another valve. The sixth valve (dump valve) for dumping the spent material may preferably be a large bore ball valve. The screen for retaining the granular material at the bottom of the container may comprise a cylindrical screen arranged coaxial with an axis of the bore of the dump valve, and sealed at its upper and lower peripheral edges so as to prevent granular material from passing the screen to a liquid outlet. The pumping means for the liquid treatment apparatus may comprise conventional liquid pumps. These may be electrically or hydraulically operated. Having hydraulically operated pumps may be preferable in that a single hydraulic pressure supply powered by the engine of a vehicle on which the apparatus is mounted may be used to provide power for the pumps, blowers/fans and other equipment.

The control means for the liquid treatment apparatus may comprise a . programmable logic controller whereby the condition of the various components such as filters, adsorbers, the evaporator/degasifier, the heater, may be monitored and the various, valves, pumps, compressors, blowers, fans etc. may be operated to maintain the desired operating conditions, and to control replenishment of the granular adsorber material. The apparatus may thus be programmed to operated semi automatically or automatically depending on requirements.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which:

Figure 1: is a schematic plan view of a liquid treatment apparatus according to an embodiment of the present invention;

Figure 2: is a schematic view from a right side of the liquid treatment apparatus of FIG. 1 showing details of a heating system and an arrangement of filter/adsorber towers and an evaporator degasifier; Figure 3: is a schematic view from the right side of the liquid treatment apparatus of FIG. 1 showing an arrangement of granular material inlet and outlet valves for the filter/adsorber towers;

Figure 4: is a schematic sectional view of a lower part of a filter/adsorber tower showing an arrangement of a screen element and a rotary discharge valve;

Figure 5: is a schematic view from a left side of the liquid treatment apparatus of FIG. 1 showing an arrangement valves for the filters and coalescer;

Figure 6: is a schematic view from a left side of the liquid treatment apparatus of FIG. 1 showing an arrangement of pressurisation valves for the filter/adsorber towers;

Figure 7: is a schematic sectional view of a filter/adsorber tower showing an arrangement valves;

Figure 8: is a cross-sectional view of aspects of the filter/absorber tower of Figure 7, and

Figure 8A: is an enlarged view of the encircled portion of Figure 8.

BEST MODE FOR CARRYING OUT THE INVENTION

In Figure 1, there is shown a schematic plan view of a liquid treatment apparatus according to an embodiment of the present invention generally indicate by arrow 1. The apparatus 1 which is mounted on a truck or trailer (not shown in the figures) comprises an inlet 2 for inputting liquid to be treated by the apparatus 1 into the apparatus 1, an outlet 3 for discharging the liquid from the apparatus 1 after treatment by the apparatus 1, a heater generally indicated by arrow 4 for heating the liquid by means of heat exchangers 4a, 4b and 4c, element type filters 5, 6 and 7 and granular material filter 8 for filtering contaminants from the liquid, a coalescer 9 for coalescing liquid impurities in the liquid for subsequent removal from the liquid, adsorber towers 10, 11, 12 and 13 for adsorbing contaminants from the liquid, an evaporator/degasifier generally indicated by arrow 20 for evaporating and separating out liquid and gaseous contaminants contained in the liquid, a hydraulic power supply 22 (driven by the truck motor or an electric main drive) for providing hydraulic power for the apparatus, and hydraulically driven pumps 14, 15 etc. for pumping liquid from the inlet 2 through the medium temperature heat exchanger 4a, filters 8, and 5, coalescer 9, lower temperature heat exchanger 4b, adsorbers 10, 11, 12, 13, filters 6 and 7, and evaporator/degasifier 20 to the outlet 3.

The heater 4 as shown in more detail in FIG. 2 comprises a Thermix™ oil heating system 30 wherein a primary liquid is heated by an oil burner supplied with diesel fuel from a fuel tank 32, and passed to a heat exchanger 34 which has primary heating liquid pipe coils supported inside and which is filled with the liquid to be treated by way of an inlet 36 and 38. Additional primary heating coils are also connected to the lower temperature heat exchanger 4b and the higher temperature heat exchanger 4c. A control system is provided (not shown in the figures.) for controlling the output from the burner so as to maintain an outlet temperature from the heat exchanger of between 20°C to 75°C. As shown more clearly in FIGS 2 and 3, the filter tower 8 and adsorber towers 10, 11, 12, 13 are in the form of upright cylindrical containers. These are filled with a predetermined amount of Attapulgite™ granular adsorbent material. Each of the towers is provided respectively with liquid inlets 40, 42, 44, 46, 48 and outlets 50, 52,54, 56, 58, and granular material inlets 60, 62, 64, 66, 68 and outlets 70,72,74,76,78.

As shown more clearly in FIG. 4 which gives details of the outlet region for filter tower 8 which is typical of the outlets for the adsorber towers 10,11,12,13, the liquid outlet 50 has a cylindrical screen 80 for containing granular material 82 in the tower 8 while allowing liquid to pass from the tower 8 to the liquid outlet 50. A dump valve 84 in the form of a large bore ball valve for dumping the spent granular material 82 is mounted beneath the screen 80 at the granular material outlet 70. The screen 80 is arranged coaxial with an axis of the bore of the dump valve 84 and is sealed at its upper and lower peripheral edges 84, 86 so as to prevent granular material 82 from passing the screen 80 to the liquid outlet 50.

Commercial Zeta Plus® filters made by Process Filtration Products of the USA having a filter media with a high contaminant holding capacity are used for the element filters 5,6,7 shown in FIG. 5. Filters 5 and 6 are both fitted with 5 to 10 micron mesh cartridges, filter 7 is fitted with a 5 to 7 micron cartridge, and the coalescer which operates at an approximate pressure differential of 15psi is fitted with a coalescer cartridge. As shown in FIG. 5, the filter 5, coalescer 9, and filters 6 and 7 are each provided with respective inlets 90,92,94,96 and outlets 91, 93,95,97, with filters 6 and 7 connected in series. Any one of the filters or coalescer may be isolated by means of isolation valves 100,102,104,106 and 101,103,105,107 provided on the respective inlets and outlets so that the filter element or coalescer element can be changed when required without interrupting the operation of the apparatus. Outlets from the filters can be directed to the buffer collector tank 150 by means of the outlet isolation valves 101,103,105,107 so that the filter/coalescer case can be drained a certain amount to avoid overflow when a new element is fitted. Filter condition indicators (not shown in the figures.) are incorporated into a control system of the apparatus to indicate when the filter elements or coalescer element require changing.

The evaporator/degasifier 20 as shown in FIG.l and in more detail in FIG. 5 comprises a vacuum chamber 110 having an inlet 42 and outlet 44, an evacuating device generally indicated by arrow 112 (FIG.l) for producing a vacuum of up to lOTorrs in the vacuum chamber 110, and a bank of thin tubes generally indicated by arrow 114 . As shown in FIG. 1 the evacuating device 112 comprises a lobe type or star type hydraulic pump 114 housed inside a sealed container 116, with an outlet 118 from the container connected to an outlet from the pump 114 and an inlet 120 to the container connected to the vacuum chamber 110 of the evaporator/degasifier. The outlet 118 discharges into a second buffer tank

125 for subsequent return to the system. Hydraulic lines 119,120 for supplying power from the hydraulic pump 22 to power the pump 114 are passed through sealed openings in the wall of the sealed container 116.

The tubes 114 in the vacuum chamber 110 are arranged in vertical orientation adjacent to each other, and supported at upper and lower ends by baffle plates 130, 131 respectively which are fixedly attached to the vacuum chamber 110 and which seals a passage between the tubes 114 so that liquid can only flow though the tubes 114 in a downward direction. Heating liquid surrounding the tubes 114 is heated by the higher temperature heat exchanger 4c. In the present embodiment 152 tubes made from 20mm inside diameter stainless steel 1200 mm long are provided inside the chamber 100 , so that with a flow rate of 30 litres per minute a film thickness of approximately 5-15 microns is obtained, and under a vacuum of 9 - 10 Torr and a temperature of 50°C the residual gas/liquid impurities in the liquid can be reduced to a sufficient amount, so that the liquid treatment apparatus 1 can treat the liquid in a single pass.

The material handling system for replenishment of the adsorbent filter material contained in the filter tower 8 and adsorber towers 10, 11, 12, 13 comprises a pressurisation system having a hydraulically driven compressor 130 (FIG. 1) which can be selectively connected to the respective towers 8,10,11,12,13 by means of three way valves

140,142,144,146, 148 (FIG. 6). A negative pressure can be applied to the respective towers 8,10,11,12,13 by connecting their respective liquid outlets

50,52,54,56,58 (FIG. 3) to a liquid buffer container 150 (FIG. 1) in which a negative pressure has been produced by the evacuating device 112. With this arrangement a differential pressure across the adsorbent/filter material of from 30psi to 2psi may be produced while maintaining the pressure inside the tower below 30psi. Hence the tower is not required to conform to stringent pressure vessel design standards thereby reducing design and manufacturing costs.

A hydraulically driven induction fan 152 (FIG. 1) discharging into a dust collector 153, is connected by means of the three way valves 140,142,144,146,148 (FIG.6) to evacuation outlets 160,162,164,166,168 (FIG. 3) of the respective containers 8,10,11,12,13. This provides a low pressure to draw the granular filter/adsorber material into the tower via the respective inlets 60,62,64,66,68 (FIG. 3) when the valve is turned to open the tower to the induction fan 152. The arrangement of the evacuation outlets of the towers is shown more clearly in FIG. 7 which shows an arrangement for tower 8 which is typical of the other towers 10,11,12,13. In this arrangement, the granular material inlet 60 is provided on the side wall of the tower 8 while the evacuation outlet 160 is provided centrally in the top of the tower 8.

Granular material is selectively supplied to the respective tower 8,10,11,12,13 from a storage hopper 170 (FIG. 3) via a distributor valve 172. The distributor valve 172 comprises a rotatable disk with internal passages arranged so as to align with respective outlets to the towers depending on a selected rotation of the disc. The storage hopper 170 is filled with sufficient material for replacement of one tower by connecting a central upper outlet to the induction fan 152 to thereby draw in granular material from a supply tank which may be on a trailer towed behind the liquid treatment apparatus.

The before-mentioned liquid buffer container 150 of the present embodiment has a capacity to hold the total volume of liquid drained from one tower as well as the total volume of liquid from one of the filters or the coalescer. Hence spillage which can occur when replacing a filter/coalescer element can be avoided by first lowering the level in the filter/coalescer casing. Additional provision is also provided for spillage in the form a of a sump tank 175 (FIG. 2) which collects any spillage or leakage and recycles this back into the apparatus 1. Both the dump container 150 and the sump tank 175 are provided with level sensors and valving so that when a predetermined level is reached the liquid is pumped back into the apparatus 1. Operation of the various components of the apparatus such as valves, motors, pumps and compressors is controlled by a Programmable Logic Controller 180 mounted at the rear of the apparatus 1.

With respect to Figures 8 and 8a of the drawings provides means for producing a thin film flow by providing a liquid flow path provided by the vertically orientated tubes 114 supported by baffle plates 130,131. As indicated in the Figures the openings to the vertically orientated tubes are disposed above the baffle 130 so that a thin film of liquid is drawn from the surface of the baffle plate, initially upwards and then over the top surface of each tube in the manner indicated by Figure 8a. The extent to which each tube end extends above the surface of the baffle plate may be varied by design to suit different liquids but the arrangement has been found to provide an excellent even liquid film flow.

A description of an operation of the apparatus 1 of the present invention for treating transformer oil will now be given with reference to the drawings.

The apparatus 1 which has been previously charged with transformer oil is first driven to a transformer installation requiring treatment of its insulation oil. The inlet 2 to the apparatus 1 is connected to the oil outlet on the transformer casing and the outlet 3 from the apparatus 1 connected to the oil inlet on the transformer. The apparatus is then switched and the oil temperature in the primary heating coil of the heat exchanger brought up to a temperature of approximately 55°C. The circulating pump 14 is then switched on so as to circulate oil from the transformer outlet, through the apparatus 1 and back to the transformer inlet. In this operation, the oil passes though the medium temperature heat exchanger 4a to warm the oil, the granular material filter tower 8 to remove any larger particles and colloidal contaminants from the oil, the element filter 5 to remove smaller particles, the coalescer 9 to remove the majority of water, and then to the heat exchanger 4b where it is reheated to approximately 40°C. The oil then passes through adsorber towers 10,11,12,13 to further remove contaminants such as water, acidic compounds, and other products of oxidation. The oil then passes into the element filters 6 and 7 to remove very fine particles which may have been picked up in the adsorber towers.

Subsequently the oil flows through a pressure reduction valve into the top of the evaporator/degasifier 20 where it is allowed to flow downwards as a thin film on the tubes 114 of the evaporator/degasifier 20 while being subjected to a vacuum of approximately lOTorr produced by the vacuum device 112. Remaining liquid and gases contained in the oil are evaporated off and removed from the oil so that a required degree of purity is achieved. The oil is then pumped back to the inlet to the transformer completing the operation. Since the apparatus is able to achieve a satisfactory purification of the oil in one pass, the oil treatment operation is completed once the whole contents of the transformer have been circulated through the apparatus 1.

Replenishment of the adsorbent contained in the adsorbent towers 8, 10,11,12, and 13 will now be described. Adsorbent replenishment is called for after a predetermined period of operation determined by a timer in the programmable logic control unit 180.

At first a sufficient amount of clean adsorbent is loaded into the holding hopper 170 using the induction fan 152 to reduce the pressure in the hopper 170 so that adsorbent may be drawn into the hopper through the inlet pipe from a supply tank carried on a trailer behind the truck. The filter/adsorber tower requiring replenishment is then isolated from the system by closing off the liquid inlet. The following description will be given in relation to filter/adsorber tower 8 as representative of the other towers 10,11,12,13. The liquid inlet valve 40 is thus closed off to isolate the tower 8 from the system. The liquid outlet 50 is then switched to bypass the system and open the outlet to the buffer container 150. The pressurisation valve 140 is then opened to allow the container to be pressurised to a pressure of 30psi thereby driving oil from the tower out via the bottom bypass valve to the buffer container 150. The outlet 50 isolation valve is then closed to allow the pressure in the tower to build up to 30psi. The bottom dump valve 84 then opens to allow the granular material contained on the tower to be ejected into an open container positioned close by. The pressurisation valve 140 is then closed and the bottom dump valve 84 closed. The top evacuation outlet 160 and granular material inlet 60 valves are then opened, and a blower which applies a pressure to the hopper 170 and the induction fan 152 are turned on to cause the adsorbent to be drawn from the hopper 170 into the tower. Once the tower has been filled with the charge from the hopper 170, the top evacuation outlet 160 valve and granular material 60 inlet valves close. A pump back valve then opens and a pump back pump is switched on for approximately 3 minutes to pump oil from the dump container 150 back into the tower The pump back pump is then switched of and the inlet and outlet isolation valves opened so that the tower is connected back into the system.

In the above disclosure and description the material handling means and evaporator/degasifier means are incorporated into a liquid treatment apparatus. However the material handling means and evaporator/degasifier means of the present invention are not limited to this application and may be used independently or respectively in other apparatus where granular material contained in containers is to be replenished, or where liquid containing liquid and gaseous impurities is to be purified.

For example the apparatus and methods may be applicable to the treatment of fuels such as jet fuel which require a high degree of purity especially from moisture which is susceptible to freezing at low operating temperatures.

I believe the advantages of my invention to be as follows, however it should be appreciated that all such advantages may not be realised on all embodiments of the invention, and the following list is therefore given by way of example only as being indicative of potential advantages of the present invention. Furthermore, it is not intended that the advantages of the present invention be restricted to those of the list which follows.

1. The apparatus enables a fully automatic Hquid treatment operation to be carried out.

2. The apparatus is self contained and portable and can be easily moved between treatment sites.

3. The use of a low cost granular material as a filter as well as an adsorber helps reduce the filter load on more expensive element type filters.

4. The evaporator/degasifier enables single pass purification of the liquid thereby reducing operating costs and time. Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.

Claims

THE CLAIMS DEFINING THE INVENTION ARE:

1. A process for treating contaminated liquids, said process comprising the steps of;

(b) heating the filtered liquid in a heater;

(c) passing said heated liquid through an adsorber containing a granular adsorbent capable of removing contaminants from said liquid; and

(d) degasifying the liquid.

2. The process of claim 1 including the steps of;

(c) allowing liquid contained in said container to flow out of said container through a liquid outlet as a result of said pressure differential, while preventing granular material in said container from flowing out of said container,

(d) closing off said liquid outlet ,

(e) discharging said granular material from said container by opening a granular material discharge outlet to allow granular material contained therein to flow out of said container under a pressure differential,

(f) closing said granular material outlet and reducing the pressure in said container, and (g) opening a granular material inlet to said container to allow a predetermined amount of granular material to flow into said container.

3. The process of claim 2, wherein said step of applying a pressure differential across said granular material involves pressurising an inlet to said container and connecting said liquid outlet from said container to a collection chamber (buffer collection tank), and the step of discharging granular material from said container involves allowing a pressure inside said container to increase to a predetermined pressure above atmospheric pressure, and then opening said discharge outlet to discharge granular material under the resultant pressure differential into a container at atmospheric pressure, and recycling liquid collected in said collection chamber back into said liquid treatment apparatus.

4. The process of any one of claims 1 to 3 wherein degasifying comprises the steps of;

(b) causing said liquid to flow over a surface or surfaces inside said container as a thin film, so that liquid contaminants contained in said liquid evaporate from said liquid, and gaseous contaminants dissolved in said liquid come out of solution and separate from said liquid, and until a predetermined purity of liquid is obtained, and

(c) pumping said purified liquid from said container.

5. A liquid treatment apparatus for removal of contaminants from a liquid, said apparatus comprising: - inlet means for inputting a liquid to be treated by said apparatus into said apparatus, outlet means for discharging said liquid from said apparatus after treatment by said apparatus, heating means for heating said liquid, filter means for filtering contaminants from said liquid, adsorption means for adsorbing contaminants from said liquid, evaporator/degasifier means for evaporating and separating out liquid and gaseous contaminants contained in said liquid, pumping means for pumping said liquid from said inlet means through said filter means, adsorption means, heating means, and evaporator/degasifier means to said outlet means, and control means for controlling the operation of various components of the apparatus to enable semi automatic or fully automatic operation.

6. A apparatus as claimed in claim 5, further comprising coalescer means for coalescing liquid impurities in said liquid for subsequent removal from said liquid.

7. Apparatus as claimed in claim 5 or claim 6, further comprising material handling means for facilitating replacement of adsorbent/filter material in said filter means and said adsorber means.

8. Apparatus as claimed in any one of claims 5 to 7 wherein said heating means comprises a heat source for heating a primary heating fluid, and a heat exchanger for exchanging heat from said primary fluid to said Hquid being treated.

9. Apparatus as claimed in any one of claims 5 to 8 wherein said evaporator/degasifier means comprises; a vacuum chamber having an inlet and an outlet, means for producing a vacuum in said vacuum chamber, and means for producing a thin film flow of said liquid inside said vacuum chamber.

10. Evaporator/degasifier means comprising a vacuum chamber having an inlet and an outlet, means for producing a vacuum in said vacuum chamber and means for producing a thin film flow of a liquid inside said vacuum chamber.

11. Evaporator/degasifier means as claimed in claim 10 wherein said means for producing a thin film flow incorporates a liquid flow path provided by vertically orientated tubes supported within said vacuum chamber by at least one baffle plate onto which the incoming liquid is introduced prior to passing through said tubes.

12. Evaporator/degasifier means as claimed in claim 11 wherein the surfaces of the vertically orientated tubes are heated.

13. Evaporator/degasifier means as claimed in claim 11 or claim 12 wherein openings to the vertically orientated tubes are disposed above the surface of the baffle plate.

14. A process substantially as herein described with reference to the accompanying drawings.

15. Apparatus substantially as herein described with reference to the accompanying drawings.